


With The Tide

by Masrrkan



Category: Free!
Genre: Alpha/Beta/Omega Dynamics, Fluff, Foursome - M/M/M/M, M/M, Mating Cycles/In Heat, Mpreg, Polyamory, a lot of Ai-chan love, also the rating will most likely change, mermaid, mermaid au, probably won't update this often, will add more characters and ships when and if they show up
Language: English
Status: In-Progress
Published: 2016-02-02
Updated: 2016-03-09
Packaged: 2018-05-17 19:38:47
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 2,004
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5883007
Author URL: https://archiveofourown.org/users/Masrrkan/pseuds/Masrrkan
Summary: <blockquote class="userstuff">
              <p>A young Ai seeks out mermen to become a member of a pack.</p>
            </blockquote>





	1. Chapter 1

**Author's Note:**

> New fic! Just something to play around with, I guess. Probably gonna become a fic I'll take requests for, so if you wanna see something happen with the characters and story, send me an ask at ghoulishken.tumblr.com or just leave a comment!

The gentle glow of sunlight through the surface of the ocean reached out to Ai, caressing his face and body until his skin glowed a dazzling white. The silver scales on his tail and fins shimmered excellently as he rose from his comfortable bed of sea sponges.

The merman stretched out his arms, sighing contentedly while he pushed back his hair and glanced around with his wide, curious blue eyes.

Today was a new day. Today, Ai would find a new pack to join. The wide expanse of the ocean held many other merfolk, and there had to be at least one pack that wanted his company as an Omega.

The merman twirled through the water, feeling it mold around his body as he swam quickly towards the shipwreck behind the drop off. Sharks always had a tendency to roam there, and sharks always tended to be Alphas, as well.

Ai smiled as he peaked over the ledge. He had attempted to search the wreck the day before, but night came too soon and the darkness had left the Omega feeling anxious. So, after sleeping off his worries, he was finally ready to search.

As he swam down, he felt a slight change in water temperature. It was slightly dimmer off the drop, and a bit cooler. Ai shivered a bit when he noticed movement in the ship, and the merman eagerly made his way over, hoping that this Alpha would be in need of an Omega to bond with.

Ai clutched either side of a broken window frame and pushed his upper body inside, looking around the dark, wooden wreckage.

"Hello? Is anyone in here?" Ai asked, slowly making his was through the window to swim around the empty ship. "Hellooo?" He called out again, and suddenly, felt a hard grip on his wrist.

"Shh!" The merman before him hissed, and Ai covered his mouth with his free hand to keep himself from yelping in surprise. "This place is practically a breeding ground for sharks and Alphas, what are you doing here all alone??"

Ai made a strangled noise when he was pulled out of the ship, the stranger shark swimming quickly back up to the drop off. "Um, well, I was looking for a pack." The Omega said, once his hand was released. "All remoras at my age look for sharks to form a pack with."

"Seriously?" The Alpha blinked his crimson eyes and rubbed the back of his neck. "Well, I guess I don't have any Omegas in my pack. It's pretty small now, though. You can join, if you wanna."

"Yes!" Ai nodded excitedly, a big grin on his face. "My name is Ai! Though, it's actually just short for Aiichirou. Everyone back home calls me that." He giggled.

"Ai, huh? That's cute. It suits you." The merman grinned, and the Omega almost gasped over how sharp his teeth were. "I'm Rin. Short for Rin." He laughed, as did Ai. "Come with me, and I'll take you to my pack." He waved a hand as he began to swim, and Ai almost had a hard time keeping up with his powerful tail.

"Are you the leader of your pack?" Ai asked, keeping himself tucked under Rin. "You seem like a high ranked Alpha." He added, glancing up.

"Me? Nah. I'm the lowest ranking in the pack, actually." Rin chuckled, and slowed down a bit to keep from exhausting Ai. "The leader is named Seijuurou, and then there's Sousuke, who just barely outranked me." He pouted a bit, then frowned when the remora giggled.

"Wow, and here I thought you were the strongest shark I've ever met." Ai beamed up to Rin, and didn't miss the way he blushed.

"Well, I mean..." Rin cleared his throat, coughing softly as they swam at a leisurely pace. "I could totally outrank both of them if I wanted. These teeth don't belong to someone who couldn't easily become the Alpha Male of the pack." He boasted, puffing out his chest in an attempt to impress Ai.

"Oh really?" The deep, commanding voice of an Alpha sent shivers down Ai's spine, and by the looks of it, the same happened with Rin. "If you can outrank me so easily, then why haven't you?"

Rin's expression grew a bit frightened, and annoyed at the same time. "I'm... Just trying to impress the Omega. I wasn't being serious, Seijuurou." He replied, turning to meet piercing orange eyes.

Ai turned as well, and his jaw dropped at the sight of such a huge Alpha. His tail was huge and powerful, and his jaw was set strongly. He was handsome, as well, probably as much as Rin.

"H-hello!" Ai spoke up, his cheeks flushing a bright pink when Seijuurou glanced over. "I'm Ai, an Omega, and I wanna join your pack!" He continued on before the Alpha could say anything.

Seijuurou glanced at Rin, who shrugged, and then back at Ai. "Well, I won't say no. We kinda need an Omega around to help with ruts and stuff, and especially if we want to expand our group, we need someone to have pups." He crossed his arms over his chest, biting his lip in thought.

"I'm okay with that! Alpha's need an Omega to help keep some order, right?" When Seijuurou nodded, Ai grinned wide.

"Yeah, that's true. Well! Then we better find Sousuke. I'm sure he'll be excited about this." Seijuurou grinned at Rin, who nodded and reached out to Ai.

"Sousuke is really bull headed and stupid, so be nice to him." Rin squeezed Ai's hand when the Omega took it, and the three began swimming.

"Don't listen to Rin, doll. He's just jealous that Sousuke is stronger than him." Seijuurou laughed, and swerved around a big pillar of coral. "Oh, he's up against the surface again." He sighed, pushing back his hair with a frown.

"He's probably trying to relax. He had a bad rut a few days ago, so I'm guessing he's still in a bad mood." Rin spoke, his expression tired and bored. "Ai, do you wanna go say hi? He won't bite, I promise."

"Hmm?" Ai looked up at the massive merman gliding in circles along the surface of the ocean, his tail just skimming it. "Wow." The Omega whispered, his eyes widening. He must be lucky to find a pack full of handsome Alpha's. "That's Sousuke?"

"Yep. Now, go on, say hi." Rin smiled and gently shoved Ai up, shooing him away as he settled back beside Seijuurou.

Some anxiety welled up in the merman as he approached Sousuke. His tail was longer and most certainly stronger than Seijuurou. He ever looked more muscular! How did Seijuurou outrank someone as monstrous as him?

Before Ai could force out a "Hello", Sousuke was looking at him. His teal eyes almost paralyzed the remora, and the smile he gave him could have been enough to put Ai into a coma.

"Hey," Sousuke started as he swam a bit closer. "you came with Rin and Seijuurou?" He asked, and chuckled when Ai nodded. "I'm guessing you know I'm Sousuke. Nice to meet you."

Ai felt his heart beating quickly in his chest, but he still managed to give his own brilliant smile. "I'm Ai. I met Rin a bit ago, and Seijuurou is letting me into the pack. I'll be your new Omega from here on out!"


	2. Chapter 2

**Notes for the Chapter:**

> Sorry it's been so long! Here's an update!

“Where are we going again?” Ai asked, looking up at Rin with a small pout. “We've been swimming aimlessly for days.”

“We're trying to find new pack members, and hopefully a better place to make as our breeding ground.” Seijuurou answered, his tone on the edge of sounding annoyed. “Just be patient.”

Since Ai had joined the pack, they've done nothing but keep in one direction. They've yet to see any other merfolk, and none of the Alphas had even tried to touch him outside of hand holding.

To the Omega, he felt like this was all incredibly boring. Did all packs do this? Is it normal for an  Alpha to not touch an Omega unless they were in a rut or heat, respectively? Ai felt like he hadn't done much, if anything at all, for his Alphas.

Several more days had gone by, and finally, they began to pass more merfolk. It seemed as though these waters were popular as a resting ground for those in heat or rut, which made all three Alphas rather uncomfortable.

“Is there a reason we can't at least take a break and rest for a bit?” Ai asked once Seijuurou demanded that they carry on their merry way.

Seijuurou turned to him, looking particularly frustrated with the remora. “Alphas in rut and Omegas in heat aren't things we need to be around.” He spoke, voice surprisingly calm. “We don't need you getting hurt because some hormone-fueled Alpha can't keep his hands to himself.”

Ai stared for a moment before he sank a bit, being sure to stay close to Seijuurou’s side as he began swimming again. “I see. Thank you for looking out for me.” The Omega smiled, and felt warmth spread through his chest when the redhead ruffled his hair.

“No problem, doll. It's my job to keep you safe.” Seijuurou grinned.

“Stop hogging him, Sei.” Rin frowned as he quickened his pace to swim closer to Ai. “Sousuke and I wanna be close to him too.” He pouted.

“Sorry, sorry.” The head Alpha laughed and slowed down a bit before leaning in a bit to Ai, making the remora lean away to avoid their faces touching. “Actually, we should probably mark Ai pretty soon.”

That made the Omega perk up, flashing them a big grin. “Really? Would you do that?” Ai asked excitedly and grabbed Seijuurou's hands tightly.

“Mmh, I just wasn't sure when to do it. Once you're marked, you'll start having heats, and that means babies.” Seijuurou hummed in thought, looking between Rin and Sousuke who were close beside the Omega. “If we do, we'll have to decide who goes first once you enter your heat.”

Rin made a face and rolled his eyes. “Shouldn't we just let him decide who he wants to spend the heat with, though?” He looked at Sousuke, who shrugged, and them to Ai.

“Um…” Ai looked down at the sand below them before he glanced back up. “But what if I kept asking for the same person?” That wouldn't be fair.” He mumbled. “If I kept asking for Rin and not for anyone else then I wouldn't be able to having anyone elses pups.”

“Which is why we need to decide who will go.” Seijuurou said. “I vote we go in order of rank. So your first heat will be with me, the next will be Sousuke, then Rin, and we repeat.” The Alpha grinned widely, and Ai nodded in agreement.

“I like that! So I get an entire heat with each of you.” Ai leaned in to kiss Seijuurou's cheek, then quickly went to kiss Rin's, and finally Sousuke’s. “So, when will you mark me? I wanna be of use as soon as possible!!”

The three Alphas gave each other a look before glancing down to the remora again. “Soon, probably once we find a better place to rest.” Seijuurou began swimming again, smiling as Ai kept close to his side.

“You could start your heat the day we mark you, so it would be a good idea to find a reef.” Sousuke poked Ai's arm to get his attention, and couldn't help but smile when their eyes met. “A reef with a lot of sponges would be best, so you have somewhere to lay down.”

“Mhm, exactly.” Seijuurou nodded. “Which is why we need to keep moving, okay? We should also grab some food before it gets dark.”

The rest of the night went nicely after that, and Ai couldn't wait until they finally marked him so he could start having pups and being of use to the pack.

**Notes for the Chapter:**

> Contact me at ghoulishken.tumblr.com if you want to send me a request for a ship!

**Author's Note:**

> I hope you liked this new little thing I thought up! Feel free to send some asks at my tumblr (at ghoulishken.tumblr.com !) or leave a comment!


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